Fossils can be formed from:
- hard body parts such as shells or bones
- parts of organisms which haven’t decayed (dead plants and animals can be preserved in tree resin or ice.
- casts or impressions (foot prints or burrows)
What is a fossil?
Preserved remains of a dead plant or animal.
What can scientists learn from fossils?
How organisms have changed as life developed on earth.
What can cause a species to become extinct?
- new diseases
- new predators
- new, more successful competitors
- changes to environment/climate
- catastrophic events (eruptions or asteroids)
- human activities
How did the dodo become extinct?
Island colonised by humans. Humans ate them as they were easy to catch. New competitors (rats, cats) ate their eggs.
New species can arise due to …..
Isolation
What is genetic variation?
Where each population has a wide range of alleles that control their characteristics.
What is natural selection?
Where the alleles which help an organism to survive are selected in each population.
What is speciation?
Where the populations become so different that successful interbreeding cannot happen anymore.
Which conditions are needed for fossilisation?
Low oxygen levels and cold.
What’s the most likely reason that early life forms left few traces behind?
Most animals were soft bodied so didn’t fossilise well.